Hi bobt,
You'll find the M80s will present a very wide and deep soundstage (if the source material is well recorded); in addition, the M80s will be much more transparent and musically accurate than the old Polks.
Are those Polks of yours one of the models that used the cross-cancellation circuitry to expand the soundstage? That effect could be quite compelling or bizarre, but it only worked well if you were precisely in the sweet spot between the two speaker. The effect collapsed if you were anywhwere off-axis or even turned your head at an angle.
And, as others have noted, the M80s will cleanly handle many hundreds of watts per channel and deliver SPLs that are extremely loud, if desired.
Regards,
Alan
